I think it is you who misunderstood. He is asking what is higher above what, that is correct, but you both seem to misunderstand that the things he has stated are not the different ranks of the Sith, they are different classes within the Sith. You can be the Dark Lord of the Sith, but still be a Sith Assasin. They are like Jedi classes. You can be a Jedi Master, but still a Jedi Watchman. They are just titles, not your actual class. Do you sort of see what I am saying?
Am I right fellas? I mean, am I right?